The invention relates to a process for making self-curing or curable materials from distillation residues obtained in the hydrogenation of coal.
The invention is based on the condensation of the residues that occur in the extractive hydrogenation of coal and which are obtained by distilling off the low boiling components.
A process is already known whereby thermosetting materials may be obtained in this manner which have properties comparable to those of the resins from the group of phenolic plastics. In the known process there was formed a derivative by condensation of the residue with a phenol which product was then reacted in a second stage with formaldehyde resulting in a novolak-type resin. The initial hydrogenation product in this process was an extract which was formed by the hydrogenation of coal or lignite at a pressure of 50 to 80 bar and a temperature of 370.degree. to 390.degree. C. The softening point of this extract was at 100.degree. to 120.degree. C.
The acid condensation with phenol in this process was carried out in the presence of only 0.2% of hydrochloric acid of a density of 1.19 g/cm.sup.3 and 0.1% hydrogen iodide and a temperature of 100.degree. C. was observed. The ratio in the mixture of extract to phenol was about 1:2. The insoluble components of the resin in this process were not removed prior to the condensation. Rather, the second stage of the reaction with formaldehyde was then carried out with the entire mass obtained.
The thus produced novalak resin could be hardened by addition of at most 10% hexanmethylenetetramine and at a temperature of 180.degree. C. The shortcoming of this process was that a high melting point extraction residue had to be reacted with a large amount of phenol, but only a catalytic amount of acid. It was not possible in this manner to obtain an inexpensive product (Bronowetz and Taits, Chemie der festen Brennstoffe 1 (1970), pages 86-94, UDSSR). It was also known to obtain a polycondensation resin from a low temperature crude tar derived from coal and lignite after removal of the solid paraffins followed by a two-stage condensation with Formalin at 90.degree. C. in the presence, in the first stage, of hydrochloric acid, and in the second stage of ammonia. The condensation thus was effected in absence of phenol and actually had not the object to obtain a hardenable product (UDSSR-Patent No. 148 237).
Both processes, besides, did not have the objective to produce an industrially valuable resin or moldable material.
It was furthermore known to extend or dilute epoxy resin and phenolic plastics with tars from the petroleum distillation for the purpose to reduce the price of the resins. In this manner there were for instance made floorings, impregnating materials, etc. In all these mixtures the tar served only as a diluent or filler (UDSSR-Patent No. 419 542, Veba Chemie Corporation, Product-Information 22-D-169-2-4).
The present invention, therefore, has the object to obtain an inexpensive thermosetting moldable material from the residues of the extractive coal hydrogenation.